218123 has 4 divisors (see below), whose sum is σ = 221880. Its totient is φ = 214368.

The previous prime is 218117. The next prime is 218131. The reversal of 218123 is 321812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 218123 - 2⁴ = 218107 is a prime.

It is a super-3 number, since 3×218123³ = 31133334756680601, which contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1790 + ... + 1907.

It is an arithmetic number, because the mean of its divisors is an integer number (55470).

2²¹⁸¹²³ is an apocalyptic number.

218123 is a deficient number, since it is larger than the sum of its proper divisors (3757).

218123 is an equidigital number, since it uses as much as digits as its factorization.

218123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3756.

The product of its digits is 96, while the sum is 17.

The square root of 218123 is about 467.0364011509. The cubic root of 218123 is about 60.1959335450.

Adding to 218123 its reverse (321812), we get a palindrome (539935).

The spelling of 218123 in words is "two hundred eighteen thousand, one hundred twenty-three".